Method and system for operating a gas turbine engine

Abstract

A method for operating a gas turbine engine comprises providing fuel flow and compressed airflow to a combustor with a fuel-to-air ratio, the compressed airflow being from a compressed air source; detecting at least one parameter indicative of the fuel-to-air ratio being below a predetermined value; and bleeding compressed air from the compressed air source when the at least one parameter indicative of the fuel-to-air ratio is below the predetermined value to increase the fuel-to-air ratio to at least the predetermined value.

The invention claimed is: 
     
       1. A method for operating a gas turbine engine, the method comprising:
 detecting an acceleration command; 
 providing increased fuel flow and compressed airflow to a combustor with a fuel-to-air ratio in response to the detected acceleration command, the compressed airflow being from a compressed air source; 
 associating a noise level to be reduced in the combustor with the fuel-to-air ratio dropping below a predetermined value; 
 detecting the noise level to be reduced; and 
 in response to detecting the noise level to be reduced, causing a reduction of the noise level by bleeding compressed air from a transfer tube fluidly connected to the compressed air source to increase the fuel-to-air ratio of the combustor to at least the predetermined value, wherein the transfer tube includes one of a butterfly valve and a sleeve valve for selectively bleeding the compressed air into a discharge region. 
 
     
     
       2. The method as defined in  claim 1 , further comprising ceasing bleeding of the compressed air when the fuel-to-air ratio is above the predetermined value. 
     
     
       3. The method as defined in  claim 1 , comprising attaining a target rotational speed of an engine rotor and then ceasing bleeding the compressed air. 
     
     
       4. The method as defined in  claim 1 , wherein bleeding the compressed air comprises bleeding the compressed air to a bypass duct of the gas turbine engine. 
     
     
       5. The method as defined in  claim 1 , wherein causing the reduction of the noise level by bleeding compressed air comprises bleeding compressed air from a plenum surrounding the combustor. 
     
     
       6. The method as defined in  claim 1 , wherein providing the increased fuel flow and the compressed airflow comprises providing a least amount of compressed air relative to the fuel flow to prevent engine flame-out. 
     
     
       7. The method as defined in  claim 1 , comprising performing the providing increased fuel flow and compressed airflow, the associating the noise level to be reduced in the combustor with the fuel-to-air ratio dropping below a predetermined value, the detecting the noise level to be reduced, and the causing the reduction of the noise by bleeding compressed air, during an acceleration of the gas turbine engine from a ground idle state of the gas turbine engine. 
     
     
       8. A system for operating a gas turbine engine, the system comprising:
 a processor unit; and 
 a non-transitory computer-readable memory communicatively coupled to the processing unit and comprising computer-readable program instructions executable by the processing unit for:
 receiving an acceleration command for the gas turbine engine; 
 generating a command to provide increased fuel flow and compressed airflow to a combustor with a fuel-to-air ratio in response to the received acceleration command, the compressed airflow being from a compressed air source; 
 associating a noise level to be reduced in the combustor with the fuel-to-air ratio dropping below a flame instability risk condition; 
 receiving a signal indicative of a detected noise level to be reduced; and 
 in response to receiving the signal:
 generating a command causing a reduction of the noise level by bleeding compressed air from a transfer tube fluidly connected to the compressed air source feeding the combustor to increase the fuel-to-air ratio within the combustor, wherein the transfer tube includes a flow valve for selectively bleeding the compressed air into a discharge region. 
 
 
 
     
     
       9. The system as defined in  claim 8 , wherein generating the command causing the reduction of the noise level comprises causing the compressed air to bleed to a bypass duct of the gas turbine engine. 
     
     
       10. The system as defined in  claim 8 , wherein generating the command causing the reduction of the noise level comprises causing the compressed air to bleed from a plenum surrounding the combustor. 
     
     
       11. The system as defined in  claim 8 , wherein the fuel-to-air ratio comprises a least amount of compressed air to prevent engine flame-out. 
     
     
       12. The system as defined in  claim 8 , wherein the processing unit is operable to execute the receiving the acceleration command, the generating the command to provide increased fuel flow and compressed airflow, the associating the noise level to be reduced in the combustor with the fuel-to-air ratio dropping below a flame instability risk condition, the receiving the signal indicative of the detected noise level to be reduced, and the generating the command causing the reduction of the noise level by bleeding compressed air, during an acceleration of the gas turbine engine from a ground idle state of the gas turbine engine. 
     
     
       13. The system as defined in  claim 8 , wherein the flow valve is one of a butterfly valve and a sleeve valve.